Molecularly Designing a Passivation ETL to Suppress EQE Roll-off of PeLEDs

Abstract

Efficiently suppressing the external quantum efficiency (EQE) roll-off of perovskite light-emitting diodes (PeLEDs) urgently requires designing passivation electron transporting layers (ETLs) for intrinsically passivating perovskite surface defects toward next-generation illumination and display. Here, we molecularly designed the inherent passivation ETL B3PyPPM with a strong nucleophilic core-group to effectively passivate perovskite surface defects. Compared with ETL B3PyMPM, the B3PyPPM can theoretically form a tighter interaction with the perovskite surface and transfer more electrons to better passivate surface Pb2+ vacancies, leading to superior suppression of EQE roll-off in PeLEDs by reducing the trap-assisted nonradiative recombination. Experimentally, the B3PyPPM-based PeLED exhibits a higher EQE of 18.04%, greater luminance of 4.15 times, and a longer T 50 of 5.38 times than B3PyMPM-based PeLEDs, evidently proving the superior EQE roll-off suppression of the stronger nucleophilic core-group-based ETL. Therefore, this work provides important guidance for rationally designing multifunctional ETLs to achieve high-performance and long-term stability in PeLEDs.

Advancements in Interfacial Engineering for Perovskite Light‐Emitting Diodes

“…As a result, the EQE improved significantly, and EQE roll-off was effectively suppressed. [39] This study highlights the potential of interfacial surface defect passivation within the EML by employing innovative ETL materials in PeLEDs. These materials not only function effectively as ETLs but also enhance the quality of the adjacent perovskite interface, ultimately improving both device durability and efficiency.…”

“…[42] This challenge is particularly pronounced when working with blue PeLED materials due to their wide energy bandgap, making the selection of an appropriate HTL difficult while striving for optimal energy alignment, efficiency, and stability. [39] Copyright © 2023 American Chemical Society Doping strategy for hole transport layer. One effective strategy for mitigating this challenge involves enhancing existing HTL materials by incorporating noble additives.…”

Boosting the UV–vis–NIR Photodetection Performance of MoS2 through the Cavity Enhancement Effect and Bulk Heterojunction Strategy

“…Critical parameters employed to assess the light detection capabilities of the photodetector encompass EQE, R , D *, and response time (τ r /τ f ). EQE, representing the ratio of photogenerated electrons to the incident light photons, is expressed as a percentage, as illustrated in eq : , EQE = I normalph h c e P normalinc A λ normalpeak = false( I normallight − I normaldark false) h c e P normalinc A λ normalpeak where h denotes the Planck constant, c is the velocity of light, λ peak represents the peak wavelength of the incident light, and A stands for the effective exposure area (0.6 cm 2 ). Figure a–f and Figure S4 reveal a discernible negative correlation between the EQE and light intensity, alongside a positive correlation with the bias voltage.…”

Mitigating Perovskite Light-Emitting Diode Degradation Mechanisms through Forward Electrical Pulses

“…Therefore, we applied a 20 mV small amplitude alternating current (AC) signal modulated at frequencies of 5 kHz and 100 kHz. The 5 kHz frequency is used to capture defect charge capture processes and radiative recombination, while the 100 kHz frequency is used to capture charge injection and recombination processes. , For standard light-emitting diode devices, the injection barrier is relatively low, indicating simultaneous injection of both carriers. The ideal C – V curve can be divided into four regions: In the leakage current region (Region I), near 0 V, the carriers injected into the Pe-QLED device can be neglected, and the Pe-QLED can be treated as a device with a geometric capacitance C 0 . − In regions II to IV, as the voltage increases, carriers are injected into the EML.…”